Neutrophils extend into and through the wall of the appendix in a case of acute appendicitis. Clinically, the patient often presents with right lower quadrant abdominal pain. Rebound tenderness of the right lower quadrant is often noted on physical examination, as well as positive obturator or psoas sign. An elevated WBC count is usually present.

Question: What tests are useful for diagnosis of acute appendicitis?

Answer A combination of elevated total WBC count with neutrophila and increased serum C-reactive protein (CRP) has a sensitivity over 90%, and their absence has a negative predictive value >80%. Abdominal CT imaging has a sensitivity and specificity >90%.